The term Legacy Plug and Play,[1] also shortened to Legacy PnP,[2] describes a series of specifications and Microsoft Windows features geared towards operating system configuration of devices, and some device IDs are assigned by UEFI Forum.[3] The standards were primarily aimed at the IBM PC standard bus, later dubbed Industry Standard Architecture (ISA). Related specifications are also defined for the common external or specialist buses commonly attached via ISA at the time of development, including RS-232 and parallel port devices.

As a Windows feature, Plug and Play refers to operating system functionality that supports connectivity, configuration and management with native plug and play devices.[4] Originally considered part of the same feature set as the specifications, Plug and Play in this context refers primarily to the responsibilities and interfaces associated with Windows driver development.[5]

Plug and Play allows for detection of devices without user intervention, and occasionally for minor configuration of device resources, such as I/O ports and device memory maps. PnP is a specific set of standards, not be confused with the generic term plug and play, which describes any hardware specification that alleviates the need for user configuration of device resources.[6]

ACPI is the successor to Legacy Plug and Play.